Ed Conway, writing in Material World, left us with an interesting thought at the end of our previous post. This was, are silicon-graphite anodes the way forward for lithium-ion batteries, because they simply perform better? We close this short series by attempting to answer what turns out to be a complex question.
Which Way Should We Approach Silicon-Graphite Anodes?
Authoritative website Benchmark Source, takes a business-like approach to the paradigm. “Next-generation silicon-carbon anodes promise enhanced energy density compared to their graphite counterparts, but currently come at a significant cost premium,” it says.
“But novel materials often require technical and supply chain optimization to compete with incumbent technologies on cost.” The question that now begs an answer, is this: Are more space-efficient silicon-graphite anodes the way forward, despite their (initial) cost disadvantage?
Silicon-graphite has another trick up its sleeve that could tip the scales. The slippery material intercalates lithium-ions more efficiently, and could charge an electric car in fifteen minutes, per Ed Conway’s assessment.
In fact, if we added sufficient silicon to the mix, we might even compete with the time it takes to fill an auto gasoline tank. But silicon is expensive and we might reach a point where the cost-benefit timed out. So the jury is not in yet, regarding the optimum silicon-graphite blend.
Another Hurdle In the Way For These Promising Anodes
Do you remember how we compared batteries to living things when we charged them? As in the way we described graphite as swelling slightly as lithium-ions entered its loosely connected layers? But we were not worried, because graphite subsides as the ions flow back to the cathode.
Well, silicon does something similar, but far more dramatically. A silicon anode could swell 300% more than a graphite one. And that’s definitely not what you want happening in your smartphone.
So right now, we can’t label silicon-graphite anodes the way that the world of batteries will blindly follow. Silicon needs its pal graphite to moderate its enthusiasm. Although no doubt somebody will find a way around that too.
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